My Stepmom's Daughter Is My Ex

Mizuto and Yume used to date; now they've suddenly become stepsiblings.

Yume was making an effort to change her personality and looks in an attempt to reinvent herself as a model student.

Yume has somehow found herself with Mizuto's boxers in her possession.

As punishment for the underwear incident, Mizuto demands Yume go on a date with him. Yume is taken aback by the sudden development, but little did she know that it was all part of Kawanami Kogure's devious plan, a plan to shatter Minami Akatsuki's delusional dreams of marrying Mizuto only to become Yume's doting little sister. And how else to do it but to show her that Yume only has eyes for Mizuto?

Yume and Mizuto go out to buy a gift together for Mother's Day.

The first midterms of the school year are upon them. Once the top scoring student in the school's entrance exam and now a talented student at the top of her year, Yume is anxious to defend her position as a model student. She is displeased, however, to discover Mizuto’s relaxed approach to studying. The two later butt heads again, over something Mizuto did during their Japanese exam. Yume berates Mizuto for his actions while Mizuto retaliates in kind.